Ron Guth:
The 1849-O Dime is the third rarest New Orleans date from the 1840's. It is also one of the toughest dates in ALL of the 1840's to find in Mint State. In fact, it is almost as rare as the better-known 1844. However, unlike the 1844, there are no Gem examples of the 1849-O. Of the dozen or so Mint State 1849-O Dimes, MS64 remains the best grade assigned to this date.
Gerry Fortin has identified four die varieties for this date, plus several die states and rotated reverses. The most siginificant varieties of the 1849-O Dime include a Large Mintmark, a Small Mintmark, and a recut date.